Golf club strike indicator

ABSTRACT

A self-adhesive indicator which adheres to a golf club face to provide an indication of the point of impact of the golf ball on the club face is provided. It consists of a sandwich of various layers--a layer of pressure-sensitive adhesive on the bottom, followed by a layer of energy-absorbing elastomeric material on which is provided a film of a thermochromic material such as a temperature sensitive liquid crystal, followed by a top layer of clear high impact plastic.

TECHNICAL FIELD

The invention relates to golfing aids, and more particularly to devicesfor identifying and indicating the location on the club face which isstruck by the golf ball.

BACKGROUND ART

Numerous aids are available to assist the golfer in improving his or hergolf stroke. For example, it is useful to the golfer to be able toidentify the location on the club face struck by the ball so that thegolfer can modify his or her stance, grip or swing to improve the impactlocation to result in greater distance or avoid hooking or slicingshots. As with tennis racquets, golf club heads have a "sweet spot"which is the optimum location for striking the ball to provide maximumdistance and accuracy.

One golfing aid which assists in determining the location of impact ofthe golf ball on the club head in a golfer's stroke is disclosed in U.S.Pat. No. 4,826,173 Brown. It provides a hook and loop fastener, onecomponent of which covers the club face and the other component of whichis made into a ring to form the "ball". When the club strikes the "ball"the "ball" sticks to the club face to indicate the impact location. Thisapparatus however does not reproduce the striking of an actual golf ballto allow the mimicking of an actual golf shot.

Another prior art device is disclosed in U.S. Pat. No. 4,898,389 Plutt.This device uses an array of electronic transducers attached to the clubface to sense the impact of the ball and communicate electric signals toa processor which displays the point of impact electronically. Such adevice is sufficiently expensive to produce and difficult to use todiscourage widespread acceptance. A simpler device is disclosed in U.S.Pat. No. 5,033,746 Jones. this patent discloses a device for marking thepoint of impact of a golf ball on the face of a golf club. It comprisesan outer translucent sheet of one colour which is connected to anunderlying sheet of a contrasting colour. There is a layer of pressuresensitive adhesive between the two sheets such that the impact of a golfball causes the two sheets to adhere and the colour of the underlyingsheet to show through the translucent sheet in the area of impact. Thisdevice has been found to deteriorate after the impact and leave animprecise impression of the impact location. Another similar device isdisclosed in International Application no. PCT/GB89/01036, published 22Mar. 1990 under WO 90/02586. In this device, two sheets form a pocketcontaining a high viscosity coloured liquid. The pocket is mounted on aclub face by adhesive. The thickness of the viscous liquid and shape ofthe impact area indicates the point of impact of the ball on the clubface and the impact angle.

Consequently there is a need for a golf club strike indicator which isinexpensive to produce, easy to apply and remove, can be re-usednumerous times and provides an accurate impression of the impactlocation of the golf ball on the club face.

DISCLOSURE OF INVENTION

The invention provides a self-adhesive sticker or decal which adheres tothe club face. It consists of a sandwich of four layers--a layer ofpressure-sensitive adhesive on the bottom, followed by a layer ofhigh-hysteresis (energy-absorbing) elastomeric material on which isprovided a film of a thermochromic material, such as a temperaturesensitive liquid crystal, followed by a top layer of a clear high impactplastic.

BRIEF DESCRIPTION OF DRAWINGS

In drawings which illustrate an embodiment of the invention:

FIG. 1 is a perspective view of a golf club head;

FIG. 2 is a perspective view of the invention, partially exploded;

FIG. 3 is a perspective view of the invention applied to a driver head;

FIG. 4 is a perspective view of the invention applied to an iron head;

FIG. 5 is a perspective view of the invention applied to a driver head,after impact with a golf ball; and

FIG. 6 is a plan view of a further embodiment of the invention.

BEST MODE(S) FOR CARRYING OUT THE INVENTION

A golf club shown in FIG. 1, in particular a driver 10, has a shaft 12to which is attached a club head 14 of wood, metal or compositematerial. Club head 14 has a face 16 on which are cut slots or grooves18 to impart spin to the ball. Club head 14 also has a heel 20, toe 22and sole 24.

The invention 30 is shown applied to the face 16 of the driver 10 inFIG. 3 and the face 46 of an iron 40 in FIG. 4. It may have printed onits surface a grid such as that shown as 32 to guide the golfer to thepreferred location 34, or sweet spot, for a particular club head. FIG. 5illustrates the appearance of the invention on the club face afterstriking a ball, with a darkened area 36 indicating the area of impactof the golf ball on the club face. The golfer will then refer to writtenmaterial or an instructor to determine the necessary changes in stance,grip, etc. to improve the impact location.

The structure of the invention is illustrated in FIG. 2. The top layer31 consists of a clear plastic, such as a high impact polystyrene,polyvinyl chloride (PVC) or polycarbonate such as LEXAN™, of a thicknesson the order of approximately 100 to 250 microns. It may have a grid 32printed or etched onto its outer surface. Alternatively grid 32 could beprinted or etched on the lower surface of layer 31, or the upper surfaceof layer 33. Top layer 31 should be a high impact plastic so it issufficiently durable to withstand the mechanical abuse of repeatedstriking by a golf ball. It may be textured in order to providesufficient friction to impart spin to the golf ball.

Applied to the lower or rear surface of layer 31 is a film of atemperature sensitive liquid crystal, such as that manufactured and soldunder the trademark THERMAX by Thermographic Measurements Ltd. of SouthWirral, United Kingdom. Other suitable temperature sensitive liquidcrystal films are manufactured by Davis Liquid Crystals, Inc. of SanLeandro, Calif. and Hallcrest Products, Inc. of Glenview, Ill. The filmshould be a temperature sensitive liquid crystal film having atemperature response in the range 5 degrees C. to 50 degrees C. with thepreferred range covering 5 degrees C. to 40 degrees C. Such temperaturesensitive liquid crystal films change through a range of colours as afunction of temperature change. A micro-encapsulated liquid crystal filmis preferred, but non-encapsulated temperature sensitive liquid crystalfilms could also be used. While temperature sensitive liquid crystal isthe preferred material for the invention, other thermochromic materials,such as leuko dyes or other thermochromic chemical films would also beuseful in the invention.

The liquid crystal film is bound to layer 31 by an adhesive binder, suchas an acrylic binder. Applied over the liquid crystal layer is a backinglayer of black paint of 1-2 mils (0.025 mm to 0.05 mm) in thickness. Thelayer of black paint may be applied for example by screen printing.Layer 31 and adhered layers of liquid crystal and paint are adhered tounderlying layer 33 by a suitable adhesive layer, such as a pressuresensitive adhesive, applied to the back of the paint layer. Layer 33 isa layer of high-hysteresis (energy-absorbing) elastomeric foam, such asthat sold under the trade-mark ENSOLITE, of a thickness 1/32 in.-1/8 in.(0.8 mm to 3.2 mm) and preferably 1/16 inch (1.6 mm) depending on theclub for which the indicator is designed. No foam layer 33 is requiredfor the invention for use on putters. A layer of pressure sensitiveadhesive, having a relatively low level of adherence, is applied to thelower surface 35 of layer 33. A peel-off coated paper layer 37 isprovided over the pressure sensitive adhesive to cover the adhesiveuntil the device is attached to the club head.

To use the device, the paper layer 37 is peeled off and the device 30 isstuck to face 16 of club 10, as shown in FIG. 3, by applying thepressure sensitive adhesive surface of the device to the club face. Thegolfer then strikes the golf ball with the desired stroke. A portion ofthe energy of the impact of the golf ball on the club face will beconverted to thermal energy by the energy-absorbing elastomer layer 33and is conducted to the liquid crystal film. The resulting temperaturerise in the temperature sensitive liquid crystal film is temporarilydisplayed as a localized colour display, shown as 36 in FIG. 5. Thedisplay will disappear in 5 to 10 seconds as the temperaturedifferential disappears.

FIG. 6 illustrates an indicator 60 according to the invention in apreferred shape, with a target pattern 62 printed on the clear plasticlayer 64.

As will be apparent to those skilled in the art in the light of theforegoing disclosure, many alterations and modifications are possible inthe practice of this invention without departing from the spirit orscope thereof. Accordingly, the scope of the invention is to beconstrued in accordance with the substance defined by the followingclaims.

What is claimed is:
 1. A device (30) for providing a temporaryindication (34) of the area of impact of a ball, such as a golf ball, ona ball-striking face, such as a golf club face, said device having aninner surface for adherence to said ball-striking face and an outerimpact surface, said inner surface of said device comprising means forremovably securing said device to said ball striking face, characterizedin that said device further comprises:a) a sheet (31) of lighttransmitting, hard, durable material sized to fit on said ball-strikingface, having first and second surfaces, said first surface forming saidouter impact surface of said device; and b) a layer of thermochromicmaterial provided on said second surface of said sheet (31) of lighttransmitting, hard durable material.
 2. A device (30) for providing atemporary indication of the area of impact of a ball, such as a golfball, on a ball-striking face, such as a golf club face, said devicehaving an inner surface for adherence to said ball-striking face and anouter impact surface, said inner surface of said device comprising meansfor removably securing said device to said ball striking face,characterized in that said device further comprises:a) a sheet (31) oflight transmitting, hard durable material sized to fit on saidball-striking face, having first and second surfaces, said first surfaceforming said outer impact surface of said device; b) a sheet (35) ofenergy-absorbing elastomeric material having an outer and an innersurface and sized to fit on said golf club face; and c) a layer ofthermochromic material sandwiched between said second surface of saidsheet (31) of light transmitting, hard durable material and said outersurface of said sheet (35) of energy-absorbing elastomeric material. 3.The device of claims 1 or 2 wherein said layer of thermochromic materialis a layer of temperature sensitive liquid crystal.
 4. The device ofclaim 3 wherein said temperature sensitive liquid crystal has atemperature response in the range 5 degrees C. to 40 degrees C.
 5. Thedevice of claims 1 or 2 wherein said sheet (31) of light transmitting,hard durable material is a high impact plastic.
 6. The device of claims1 or 2 wherein said means for removably securing said device to saidball striking face comprises a layer of pressure sensitive adhesive. 7.The device of claim 6 further comprising a removable flexible protectivesheet (37) adhered to and covering said layer of pressure sensitiveadhesive.
 8. The device of claims 1 or 2 further comprising a lightabsorbing layer between said layer of thermochromic material and saidmeans for removably securing said device to said ball striking face. 9.The device of claim 8 wherein said light absorbing layer is black. 10.The device of claim 8 wherein said light absorbing layer is a darkpaint.
 11. The device of claim 2 further comprising a light absorbinglayer between said layer of thermochromic material and said means forremovably securing said device to said ball striking face wherein saidlight absorbing layer is adhered to said outer surface of said sheet(35) of energy-absorbing elastomeric material.
 12. The device of claim 2wherein said means for removably securing said device to said ballstriking face comprises a layer of pressure sensitive adhesive providedon said inner surface of said sheet (35) of energy-absorbing elastomericmaterial.
 13. The device of claim 2 wherein said sheet (35) ofenergy-absorbing elastomeric material is a high hysteresis elastomericfoam having a thickness in the range 0.8 mm to 3.2 mm.
 14. The device ofclaims 1 or 2 wherein said sheet (31) of light transmitting, harddurable material is provided with markings to locate a preferred area ofimpact for a predetermined ball-striking face.
 15. The device of claims1 or 2 wherein said sheet (31) of light transmitting, hard durablematerial is textured.